Hereinafter, a header used in a wireless access system will be described in brief.
FIG. 1 is a diagram illustrating an example of a normal medium access control (MAC) header used in a wireless MAN mobile communication system based on an IEEE 802.16 system which is one of a wireless access system.
Referring to FIG. 1, a medium access control protocol data unit (MAC PDD) includes six subheaders together with a generic MAC header (GMH). A subheader per PDU is inserted to the rear of the generic MAC header. Each field included in the generic MAC header will be described below.
A header type (HT) field represents a type of a header for a corresponding PDU. For example, the HT field represents whether a corresponding MAC PDU is either a generic MAC header which includes payload at the rear or a signaling header for control of bandwidth request, etc. An encryption control (EC) field represents encryption control, more particularly represents whether payload has been encrypted. A type field represents the presence of a subheader suffixed next to the header and a type of the subheader. An extended subheader field (ESF) field represents the presence of an enlarged subheader suffixed next to the header.
Also, a CRC indicator (CI) field represents whether CRC is suffixed to the rear of payload. An encryption key sequence (EKS) field represents an encryption key sequence number used for encryption if payload is encrypted. A LENgth (LEN) field represents a length of MAC PDU. A connection identifier (CID) field represents a connection identifier to which MAC PDU is transferred. Connection is used as an identifier of a MAC layer for data or message transfer between a base station and a mobile station. The CID serves to identify a specific mobile station or a specific service between the base station and the mobile station. A header check sequence (HCS) is used to detect an error of the header. In FIG. 1, a number in a parenthesis next to each field name represents bits occupied by each field.
Hereinafter, the CID used in the embodiments of the present invention will be described in brief.
In a mobile communication system, a mobile station (MS) can be classified through a user equipment identifier (UE ID) in 3GPP or connection ID (CID in IEEE 802.16). CIDs are used to identify a mobile station that performs communication with a base station if the base station and the mobile station perform communication through a common channel.
Hereinafter, a CID in a system that supports multiple carriers will be described in brief.
In the IEEE 802.16 which is one of portable Internet and wireless access systems, CID of 16 bits can be used. The CID means an address for classification and identification of connection mapped into a service flow required between peers on a MAC sub layer. At this time, the location of the CID can be indicated by the MAC PDU header.
In the wireless access system, connections between the mobile station and the base station are identified by the CID in the MAC header, wherein the CID can be matched with a service flow identifier (SFID) that defines service QoS parameters related to the CID.
The CID is allocated to each of logical connections, and one base station uses each CID set. Since CID has a length of 16 bits, the base station can use a total of 65536 CIDs. Each of the CIDs can be used depending on its use. Accordingly, predetermined CIDs are previously defined for broadcast control, and the other CIDs can be allocated to the respective mobile stations.
Examples of the CIDs allocated to the mobile stations (MSs) include basic CID, a primary management CID, a plurality of transport CIDs, and a secondary management CID. At present, the mobile communication system prescribes that a total of 16 CIDs can be allocated to one mobile station. In this case, about 4000 mobile stations can be represented by one CID set. If one mobile station has five CIDs, about 13000 mobile stations can be managed by one base station (BS) through the current CID structure.
If persistent and fixed resource regions are used for real time data communication and/or voice communication, the base station and the mobile station transmit and receive data units very frequently. At this time, although headers included in the respective data units have various kinds of information, all kinds of information are not always required.
Accordingly, the present invention is directed to a method and apparatus for transmission and reception of data using compact header, which substantially obviates one or more problems due to limitations and disadvantages of the related art.
An object of the present invention is to provide various header structures and methods for transmitting data for efficient data communication.
Another object of the present invention is to provide a compact MAC header of which size is reduced by classifying functions and uses of CID depending on respective layers (for example, MS ID and flow ID) and using identifiers optimized for each function and use.
Other object of the present invention is to provide a method for identifying each service through a MAC layer even without flow ID used in a compact MAC header and normally transmitting each service from a base station and a mobile station to an upper layer even without corresponding flow ID, whereby the size of the compact MAC header can be more reduced.
Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objectives and other advantages of the invention may be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.